linux-kernel - [patch v7 08/21] sched: scale_rt_power rename and meaning change

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Date:	Thu,  4 Apr 2013 10:00:49 +0800
From:	Alex Shi <alex.shi@...el.com>
To:	mingo@...hat.com, peterz@...radead.org, tglx@...utronix.de,
	akpm@...ux-foundation.org, arjan@...ux.intel.com, bp@...en8.de,
	pjt@...gle.com, namhyung@...nel.org, efault@....de,
	morten.rasmussen@....com
Cc:	vincent.guittot@...aro.org, gregkh@...uxfoundation.org,
	preeti@...ux.vnet.ibm.com, viresh.kumar@...aro.org,
	linux-kernel@...r.kernel.org, alex.shi@...el.com,
	len.brown@...el.com, rafael.j.wysocki@...el.com, jkosina@...e.cz,
	clark.williams@...il.com, tony.luck@...el.com,
	keescook@...omium.org, mgorman@...e.de, riel@...hat.com
Subject: [patch v7 08/21] sched: scale_rt_power rename and meaning change

The scale_rt_power() used to represent the left CPU utilization
after reduce rt utilization. so named it as scale_rt_power has a bit
inappropriate.

Since we need to use the rt utilization in some incoming patches, we
just change return value of this function to rt utilization, and
rename it as scale_rt_util(). Then, its usage is changed in
update_cpu_power() accordingly.

Signed-off-by: Alex Shi <alex.shi@...el.com>
---
 kernel/sched/fair.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a0bd2f3..c47933f 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4277,10 +4277,10 @@ unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
 	return default_scale_smt_power(sd, cpu);
 }
 
-unsigned long scale_rt_power(int cpu)
+unsigned long scale_rt_util(int cpu)
 {
 	struct rq *rq = cpu_rq(cpu);
-	u64 total, available, age_stamp, avg;
+	u64 total, age_stamp, avg;
 
 	/*
 	 * Since we're reading these variables without serialization make sure
@@ -4292,10 +4292,8 @@ unsigned long scale_rt_power(int cpu)
 	total = sched_avg_period() + (rq->clock - age_stamp);
 
 	if (unlikely(total < avg)) {
-		/* Ensures that power won't end up being negative */
-		available = 0;
-	} else {
-		available = total - avg;
+		/* Ensures rt utilization won't beyond full scaled value */
+		return SCHED_POWER_SCALE;
 	}
 
 	if (unlikely((s64)total < SCHED_POWER_SCALE))
@@ -4303,7 +4301,7 @@ unsigned long scale_rt_power(int cpu)
 
 	total >>= SCHED_POWER_SHIFT;
 
-	return div_u64(available, total);
+	return div_u64(avg, total);
 }
 
 static void update_cpu_power(struct sched_domain *sd, int cpu)
@@ -4330,7 +4328,7 @@ static void update_cpu_power(struct sched_domain *sd, int cpu)
 
 	power >>= SCHED_POWER_SHIFT;
 
-	power *= scale_rt_power(cpu);
+	power *= SCHED_POWER_SCALE - scale_rt_util(cpu);
 	power >>= SCHED_POWER_SHIFT;
 
 	if (!power)
-- 
1.7.12

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